Oxygen-Induced Embryopathy and the Significance of Glutathione-Dependent Antioxidant System in the Rat Embryo During Early Organogenesis
We investigated the effect of glutathione (GSH)-dependent antioxidant system against hydrogen peroxide (H 2O 2) formation in oxygen-induced embryopathy. Exposure of rat embryos to a high concentration of oxygen (20%) during early neurulation (day 9 to 10) significantly increased the incidence of neu...
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Published in | Free radical biology & medicine Vol. 22; no. 3; pp. 447 - 454 |
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Main Authors | , , , , , , , , , |
Format | Journal Article |
Language | English |
Published |
United States
Elsevier Inc
1997
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Subjects | |
Online Access | Get full text |
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Summary: | We investigated the effect of glutathione (GSH)-dependent antioxidant system against hydrogen peroxide (H
2O
2) formation in oxygen-induced embryopathy. Exposure of rat embryos to a high concentration of oxygen (20%) during early neurulation (day 9 to 10) significantly increased the incidence of neural tube defects compared with control embryos (10% vs 0%, p < 0.01) exposed to a low O
2 concentration (5%). The concentration of GSH in 20% O
2-exposed embryos was significantly reduced compared with that in control embryos (10.68 ± 0.72 vs 12.34 ± 0.65 nmol/mg protein, p < 0.001). The activity of
γ-glutamylcysteine synthetase (
γ-GCS), the rate-limiting GSH synthesizing enzyme increased in 20% O
2-exposed embryos (24.83 ± 0.71 vs 21.00 ± 0.94 microunits/mg protein). Increased activity of
γ-GCS was associated with increased expression of
γ-GCS mRNA. Substantial increases were also observed in the activities of glutathione peroxidase (GPX) and glutathione S-transferase (GST) in 20% O
2-exposed embryos. The formation of intracellular H
2O
2, measured by flow cytometer using 2′,7′-dichlorofluorescein diacetate (DCFH-DA), increased in isolated embryonic cells of 20% O
2-exposed embryos. The addition of buthionine sulfoxamine (BSO), a specific inhibitor of
γ-GCS, to culture media exposed to 20% O
2 produced a marked decrease in the concentration of GSH in association with a further increase in the incidence of embryonic malformations (24.4% vs. 10%, P < 0.01). The addition of 2.0 mM GSH ester to culture media exposed to 20% O
2 prevented the development of embryonic malformations through the restoration of normal GSH contents and reduction of H
2O
2. Our results demonstrated that oxygen-induced embryonic malformations were induced by increased production of H
2O
2 in the presence of an immature free radical scavenger system. We suggest that impaired responsiveness of the GSH dependent antioxidant system against oxidative stress plays a crucial role in oxygen-induced embryopathy.
Copyright © 1996 Elsevier Science Inc. |
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ISSN: | 0891-5849 1873-4596 |
DOI: | 10.1016/S0891-5849(96)00338-3 |